1. Field of the Invention
The present invention relates to an illumination mode selecting device for an illumination lamp having a plurality of illumination elements.
2. Description of the Prior Art
A change of the number of illumination elements of a lamp, such as fluorescent tubes of a fluorescent lamp, which are to be lit at one time, is sometimes desired for reasons such as energy economy.
For a fluorescent lamp having, for example, two fluorescent tubes, there are three operation modes, a non-tube illumination mode, a one-tube illumination mode and a two-tube illumination mode. In switching the operation of the illumination lamp between these three modes, a conventional method is to use a pull type switch originally equipped on the lamp. Another conventional method is to switch the illumination mode using an external switch device which is specially provided on a power distribution panel mounted on a wall or the like.
The use of the pull type switch, however, requires that the lamp itself is provided at a height from a floor which is low enough to allow the access of an operator to a string of the pull type switch and the operator must move to a position beneath the lamp. Furthermore, in case where a plurality of lamps are provided, the pull type switches thereof have to be operated respectively which is troublesome.
The use of the externally provided switch device requires special wiring between each fluorescent tube and the external switch device on the power distribution panel, causing the total cost of manufacturing the illumination system to be increased.